2.1 Chronic Liver Disease
Chronic liver disease is marked by the gradual destruction of liver tissue over time. Several liver diseases fall under this category, including cirrhosis and fibrosis (often the forerunner of cirrhosis) of the liver.
Cirrhosis is the seventh leading cause of death in the United States, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Cirrhosis is defined pathologically by the loss of normal microscopic lobular architecture with fibrosis (i.e., the growth of scar tissue due to infection, inflammation, injury, or even healing) and nodular regeneration. Because of chronic damage to the liver, scar tissue slowly replaces normal functioning liver tissue resulting in progressively diminishing blood flow through the liver. As the normal liver tissue is lost, nutrients, hormones, drugs and poisons are not processed effectively by the liver. In addition, protein production and other substances produced by the liver are inhibited.
Symptoms of cirrhosis vary, depending on severity and individuals. Symptoms may include abnormal nerve function, ascites (build-up of fluid in the abdominal cavity), breast enlargement in men, coughing up or vomiting blood, curling of fingers (Dupuytren contracture of the palms), gallstones, hair loss, itching, jaundice, kidney failure, liver encephalopathy, muscle loss, poor appetite, portal hypertension, redness of palms, salivary gland enlargement in cheeks, shrinking of testes, small spider-like veins in skin, weakness, weight loss, etc. The symptoms of cirrhosis may resemble other conditions or medical problems. Mild cirrhosis may not exhibit any symptoms at all.
The most common cause of cirrhosis is alcohol abuse. Other causes include hepatitis and other viruses (e.g., HCV as described in Section 2.2 infra.), use of certain drugs, chemical exposure, bile duct obstruction, autoimmune diseases, obstruction of outflow of blood from the liver (i.e., Budd-Chiari syndrome), heart and blood vessel disturbances, alpha1-antitrypsin deficiency, high blood galactose levels, high blood tyrosine levels, glycogen storage disease, diabetes, malnutrition, hereditary accumulation of too much copper (Wilson Disease) or iron (hemochromatosis).
Clinical signs of chronic liver disease include spider angiomas (a central arteriole from which numerous small branching vessels radiate), jaundice (yellowish discoloration of the skin), pruritus (itching), gynecomastia (enlargement of the male breast), ascites (an effusion and accumulation of serous fluid in the abdominal cavity), encephalopathy, asterixis (flapping tremor), etc. In addition to a complete medical history and medical examination, diagnostic procedures for cirrhosis may include specific laboratory tests, liver function tests, liver biopsy, and cholangiography (x-rays of the bile ducts).
Cirrhosis is a progressive liver disease, and the damage sustained by the liver is irreversible. However, with proper nutrition, avoidance of certain toxins (i.e., alcohol), vitamin supplementation, and management of cirrhosis complications, further liver damage can often be delayed or stopped. In severe cases of cirrhosis, liver transplantation may be considered.
2.2 Hepatitis C Virus Infection
The hepatitis C virus (HCV) is a blood-borne virus. HCV infection continues to be a major health problem in the U.S. and worldwide. According to the National Health and Nutrition Examination Survey (NHANES) of 1988–1994, 3.9 million Americans have been infected with hepatitis C virus, and of this group, 2.7 million were estimated to have chronic HCV infection. An estimated 50,000 cases occur annually in the U.S., making HCV infection the most common blood-borne infection in the U.S. (Wesley A. et al. Epidemiology of hepatitis C: geographic differences and temporal trends. Semin Liver Dis. 2000; 20(1):1–16). The exact prevalence of the disease is unknown, however, in Western Europe it is estimated to be 1% of the general population, 5% in some parts of Eastern Europe, and 10% in Egypt (Alberti A. et al. Natural history of hepatitis C. J Hepatol. 1999; 31 Suppl 1:17–24). The prevalence in IV drug users is as high as 58–84% (Schwimmer J. B. et al. Transmission, natural history, and treatment of hepatitis C virus infection. Semin Liver Dis. 2000; 20(1): 37–46), putting them at high risk.
HCV is a single stranded RNA virus of the Flaviviridae family. There are 6 HCV genotypes (1a, 1b, 2a, 2b, 3, 4, 5, and 6) and more than 50 subtypes. These genotypes differ by as much as 30–50% in their nucleotide sequences. The virus has a high propensity to mutate, which further adds to the difficulties in vaccine development and treatment efficacy.
The hepatitis C virus enters the body through direct blood exposure. The virus attacks cells in the liver, where it multiplies (replicates) and therefore, causes liver inflammation and kills liver cells. Regardless of mode of acquisition, as many as 50–70% of people initially infected with HCV become chronically infected (the infection does not clear up within six months), and more than 50% of the HCV-infected people will develop chronic liver disease. Most people with chronic HCV infection do not have symptoms and lead normal lives. However, in 10–25% of people with chronic HCV infection, the disease progresses over decades, and may lead to serious liver damage, cirrhosis, and/or liver cancer. The prevalence of cirrhosis, which is pathologically characterized by loss of the normal microscopic lobular architecture, with fibrosis and nodular regeneration, is above 50% in these patients. Today, HCV infection is the leading cause for liver transplants.
The current understanding of the liver pathology in chronic HCV-infected patients is that the damage is due to the host immune response and not to the virus itself. Several lines of evidence support the concept that HCV, similar to HBV, is a non-cytopathic virus in the majority of cases (Rehermann B. Cellular immune response to the hepatitis C virus. J Viral Hepatol. 1999; 6 Suppl 1:31–5; Nelson D. R. et al. Pathogenesis of chronic hepatitis C virus infection. Antivir Ther. 1998; 3 (Suppl 3):25–35; Rehermann B. et al. Cell mediated immune response to the hepatitis C virus. Curr Top Microbiol Immunol. 2000; 242:299–325). A heightened host CD8+ cytotoxic T lymphocyte (CTL) response and an elevated cytokine tumor necrosis factor alpha (TNF-a) level, which are important in limiting viral replication, become the same immune responses responsible for damage to the liver once the infection has become chronic (Takaki A. et al. Cellular immune responses persist and humoral responses decrease two decades after recovery from a single-source outbreak of hepatitis C. Nat Med. 2000; 6(5):578–82). A significant correlation has also been found to exist between the number of lobular CD8+ cells and liver enzymes levels, suggesting the prominent role of T-cell mediated cytotoxicity in the genesis of hepatocellular damage (Rehermann B., supra. (1999); Nelson D. R. et al. supra.; Rehermann B. et al. supra. (2000); Naoumov N. V. Hepatitis C virus-specific CD4 (+) T cells: do they help or damage? Gastroenterology. 1999; 117(4):1012–4; Gerlach J. T. et al. Recurrence of hepatitis C virus after loss of virus-specific CD4 (+) T-cell response in acute hepatitis C. Gastroenterology. 1999; 117(4):933–41; Lohr H. F. et al. The viral clearance in interferon-treated chronic hepatitis C is associated with increased cytotoxic T cell frequencies. J Hepatol. 1999; 31(3):407–15).
There is currently no vaccine or cure for HCV infection. Current treatments are either based on anti-viral drugs or focus on attempts to augment the anti-viral immune response. However, the results of these approaches have been largely disappointing. The current response rate to the combination therapy of interferon and ribavirin is less than 50%. The vast majority of treated patients are either non-respondents or will suffer from relapse of the disease following termination of treatment. Moreover, these treatments are associated with a high percentage of side effects.
2.3 Non-Alcoholic Steatohepatitis
Non-alcoholic steatohepatitis (NASH), also known as non-alcoholic fatty liver disease, describes a hepatic disorder typically characterized by an alcoholic pathogenesis without alcohol consumption (Blechacz B. et al. NASH—nonalcoholic steatohepatitis [in German]. Z Gastroenterol. 2003;41(1):77–90). The fat deposit in liver cells is mostly triglyceride, and the severity of NASH is directly related to the amount of fat in the liver. Histologically, if 50% of liver cells had steatosis (fatty liver accumulation), or if the total weight of fat is greater than 5% of the entire liver, then steatohepatitis can be diagnosed. NASH is further characterized by elevated serum aminotransferase activities with hepatic steatosis, inflammation, and occasionally fibrosis that may progress to cirrhosis.
The prevalence of NASH is 3–19% throughout most of the world. There are many possible causes of NASH but there isn't a definite source. The most likely causes are obesity from poor diet, diabetes, long-term use of steroids and use of tetracycline (Bacon B. R. et al. Nonalcoholic steatohepatitis: An expanded clinical entity. Gastroenterology 1994; 107:1103–91; Powell E. E. et al. The natural history of nonalcoholic steatohepatitis: a follow-up study of forty-two patients for up to 21 years. Hepatology 1990; 11:74–80). Some studies have shown sign of steatosis reversal after weight loss (Eriksson S. et al. Nonalcoholic steatohepatitis in obesity: A reversible condition. Acta Med Scand. 1986; 220:83–8; Sheth S. G. et al. Nonalcoholic steatohepatitis. Ann Intern Med. 1997; 126(2):137–45).
There is currently no established treatment that exists for this potentially serious disorder. Treatment of patients with nonalcoholic fatty liver has typically been focused on the management of associated conditions such as obesity, diabetes mellitus, and hyperlipidemia as well as discontinuation of potentially hepatotoxic drugs (Angulo P. et al. Treatment of nonalcoholic fatty liver: Present and emerging therapies. Sem Liver Dis. 2001;21(1):81–88).
2.4 Oxidative Stress and Lipid Peroxidation
Oxygen is the primary oxidant in metabolic reactions designed to obtain energy from the oxidation of a variety of organic molecules. Oxidative stress is a disturbance in the balance between the production of reactive oxygen species (ROS) and antioxidant defenses resulting in abnormally high levels of ROS (Klaunig J. E. et al. The role of oxidative stress in chemical carcinogenesis. Environ Health Perspect. 1998;106 Suppl 1:289–95). Mitochondria are the main source of ROS in the cell. Studies have shown that mitochondrial dysfunction could be a major mechanism of drug-induced liver disease (Pessayre D. et al. Hepatotoxicity due to mitochondrial dysfunction. Cell Biol Toxicol. 1999;15(6):367–73). Oxidative stress, as reflected in blood and urine by a wide range of pro- and antioxidant markers, is a significant feature of hepatitis C virus infection (Jain S. K. et al. Oxidative stress in chronic hepatitis C: not just a feature of late stage disease. J Hepatol. 2002; 36(6):805–11).
Most aerobes can tolerate mild oxidative stress, but severe oxidative stress results in damage to DNA, proteins, lipids, and carbohydrates. Lipid peroxidation is initiated by a reaction between ROS and fatty acid side chains of cell membranes. The ROS abstracts a hydrogen atom, forming a fatty acid side chain peroxyl radical, which in turn can attack other fatty acid side chains and propagate lipid peroxidation. The chain reaction continues and lipid peroxides accumulate in the membrane. Lipid peroxidation can have profound effects on cellular function by altering membrane function—increasing fluidity, compromising permeability, and inactivating of membrane-bound receptors and enzymes.
Evidence suggests that oxidative stress and mitochondrial injury play a role in the mechanisms of liver injury in chronic HCV infection (Okuda M. et al. Mitochondrial injury, oxidative stress, and antioxidant gene expression are induced by hepatitis C virus core protein. Gastroenterology. 2002;122(2):366–75; Kolen T. et al. Oxidative stress markers in hepatitis C infected hemodialysis patients. J Nephrol. 2002;15(3):302–7) and NASH (Yu A. S. et al. Nonalcoholic fatty liver disease. Rev Gastroenterol Disord. 2002;2(1): 11–9; Mehta K. et al. Nonalcoholic fatty liver disease: pathogenesis and the role of antioxidants. Nutr Rev. 2002;60(9):289–93). There is accumulating evidence that oxidative stress plays a considerable role in the development of liver fibrosis by acting in different cell types and in different signaling pathways (Gebhardt R. Oxidative stress, plant-derived antioxidants and liver fibrosis. Planta Med. 2002;68(4):289–96). Recent studies have shown that oxidative stress and lipid peroxidation play a major role in the fatty liver accumulation (steatosis) that leads to necroinflammation and necrosis of hepatic cells. Necrosis, both the piecemeal and bridging types, are associated with a poor prognosis in chronic hepatitis. Fatty tissue accumulation in the liver increases the potential for oxidative stress to trigger lipid peroxidation, leading to cytotoxic intermediates that induce inflammation and fibrosis via immunological pathways. Both in alcoholic and non-alcoholic hepatitis, steatosis and the lipid peroxidation that follows can lead to activation of stellate cells, the principal cells in the liver responsible for fibrogenesis and, ultimately, cirrhosis.
It is the goal of the present invention to formulate compositions comprising antioxidants useful for treating oxidative stress and/or lipid peroxidation, especially that associated with chronic liver disease, chronic HCV infection and NASH.
2.5 Antioxidants
2.5.1 Glycyrrhizin
Glycyrrhizin is extracted from the roots of licorice plants (Glycyrrhiza glabra, Glycyrrhiza uralensis), which are native to Turkey, Iraq, Spain, Greece, and northern China and is extensively cultivated in Russia, Spain, Persia, and India. Licorice plants have been used for thousands of years for sweetening, flavoring, and for treatment of a variety of health problems such as peptic ulcer, colds and other viral infections, microbial and parasitic infections, and cancers. It is a source of magnesium, silicon and thiamine.
Studies have shown glycyrrhizin to be effective in treating chronic HCV-infected patients who do not respond to interferon therapy (Abe Y. et al. Effectiveness of interferon, glycyrrhizin combination therapy in patients with chronic hepatitis C [in Japanese]. Nippon Rinsho. 1994; 52(7):1817–22). Experimental hepatitis and cirrhosis studies on rats found that glycyrrhizin is useful in completely reversing liver dysfunction by promoting the regeneration of liver cells and at the same time inhibiting fibrosis (Numazaki K. et al. Effect of glycyrrhizin in children with liver dysfunction associated with cytomegalovirus infection. Tohoku J Exp Med. 1994; 172(2):147–53). The intravenous administration of glycyrrhizin has been known to decrease elevated plasma transaminase enzymes in patients with chronic viral hepatitis (van Rossum T. G. et al. Intravenous glycyrrhizin for the treatment of chronic hepatitis C: a double-blind, randomized, placebo-controlled phase I/II trial. J Gastroenterol Hepatol. 1999; 14(11):1093–1099). This reduction in the levels of transaminase enzymes is mediated partly by the inhibition of immune-mediated cytotoxicity against hepatocytes (Yoshikawa M. et al. Effects of Glycyrrhizin on Immune-Mediated Cytotoxicity. J Gastroenterol Hepatol. 1997; 12(3):243–248).
Glycyrrhizin has also been shown to be effective in preventing the development of hepatocellular carcinoma in chronic HCV-infected patients (van Rossum T. G. et al. Review article: glycyrrhizin as a potential treatment for chronic hepatitis C. Aliment Pharmacol Ther. 1998; 12(3):199–205; Arase Y. et al. The long term efficacy of glycyrrhizin in chronic hepatitis C patients. Cancer 1997; 79(8):1494–500). Further, the level of thioredoxin, a thiol-containing protein induced by various oxidative stresses, was significantly higher in HCV-infected patients than in controls but was markedly decreased following treatment with glycyrrhizin (Nakashima T. et al. Thioredoxin levels in the sera of untreated viral hepatitis patients and those treated with glycyrrhizin or ursodeoxycholic acid. Antiioxid Redox Signal. 2000 Winter; 2(4):687–94).
2.5.2 schisandra (Wu Wei Zi)
Schisandra (Schisandra chinensis) is a woody vine, which is a member of the Magnoliaceae family, with numerous clusters of tiny, bright red berries (Fructus schisandra). Schisandra is distributed throughout northern and northeast China and the adjacent regions of Russia and Korea. Traditionally, the schisandra berries are harvested in the fall, dried, and then ground to be used medicinally. The berries are purported to have sour, sweet, salty, hot, and bitter tastes. This unusual combination of flavors is reflected in schisandra's Chinese name “wu-wei-zi”, meaning “five taste fruit.”
Schisandra has been studied for its hepato-protective abilities and functions as a potent antioxidant. Studies have shown that schisandra protects liver from lipid peroxidation or injury induced by toxic substances such as carbon tetrachloride (CC14) (Liu K. T., Pharmacological properties of Dibenzo [a, c] cyclooctene derivatives isolated from Fructus Schisandra Chinensis III. Inhibitory effects on carbon tetrachloride-induced lipid peroxidation, metabolism and covalent binding of carbon tetrachloride to lipids. Chem Biol Interact. 1982; 41(1):39–47). By lowering serum glutamic pyruvic transaminase (SGPT) levels, reducing ethanol induced malondialdehyde (MDA) formation, and increasing superoxide dismutase and catalase activities, schisandra and its active components have been found to be effective against viral and chemical induced hepatitis in subjects (Arase et al., supra.; Lu H. et al., Effect of dibenzo [a, c] cyclooctene lignans isolated from Fructus schisandra on ADPH induced lipid peroxidation (malondialdehyde (MDA) formation) and anti-oxidative enzyme activity. Chem Biol Interact. 1991; 78(1):77–84; Li X. J., Scavenging effects on active oxygen radicals by schizandrins with different structures and configurations. Free Radic Biol Med. 1990; 9(2):99–104).
2.5.3 Ascorbic Acid (Vitamin C)
Ascorbic acid is more commonly known as vitamin C, which is a water-soluble vitamin that has a number of biological functions. Ascorbic acid is derived from glucose via the uronic acid pathway. The enzyme L-gulonolactone oxidase, which is responsible for the conversion of gulonolactone to ascorbic acid, is absent in primates, making ascorbic acid a requirement in the diet of humans.
Vitamin C has been used to treat subjects with chronic hepatitis (Khodykin A. V. The efficacy of a diet enriched with lipotropic factors, vitamin C and vitamin B complex in patients with chronic hepatitis. Vopr Pitan. 1958; 17(2):19–29 (in Russian)). Beneficial effects of vitamin C on plasma glutathione regeneration and hepatotoxicity have also been reported (Hargreaves R. J. et al. Studies on the effects of L-ascorbic acid on acetaminophen-induced hepatotoxicity. II. An in vivo assessment in mice of the protection afforded by various dosage forms of ascorbate. Toxicol Appl Pharmacol. 1982; 64(3):380–92; Mitra A. et al. Effect of ascorbic acid esters on hepatic glutathione levels in mice treated with a hepatotoxic dose of acetaminophen. J Biochem Toxicol. 1991; 6(2):93–100; Pauling L. Vitamin C prophylaxis for posttransfusion hepatitis. Am J Clin Nutr. 1981; 34(9):1978–80).
2.5.4 Glutathione
Glutathione is a sulfhydryl (—SH) antioxidant, antitoxin, and enzyme cofactor that naturally occurs in cells. Glutathione is primarily synthesized in the liver and is involved in DNA synthesis and repair, protein and prostaglandin synthesis, amino acid transport, metabolism of toxins and carcinogens, immune system function, prevention of oxidative cell damage, and enzyme activation.
Glutathione is a powerful antioxidant. It recycles other well-known antioxidants such as vitamin C and vitamin E, keeping them in active state. In addition, glutathione is an important detoxifying agent that is found in high levels at the liver, kidneys, and lungs. Pretreatment with glutathione inhibits tumor necrosis factor-alpha (TNF-a) activity in alcoholic hepatitis (AH) (Hill D. B. et al. Antioxidants attenuate nuclear factor-kappa B activation and tumor necrosis factor-alpha production in alcoholic hepatitis patient monocytes and rat Kupffer cells, in vitro. Clin Biochem. 1999; 32(7):563–70). The protective effects of glutathione against hypoxic and cyanide-induced hepatotoxicity substantiate the role of oxidative stress in both types of injury (Younes M. et al. Protection by exogenous glutathione against hypoxic and cyanide-induced damage to isolated perfused rat livers. Toxicol Lett. 1990; 50(2–3):229–36). However, some earlier studies have shown that in individuals with cirrhosis, oral glutathione has no effect on liver function tests (Cook G. C. et al. Results of a controlled clinical trial of glutathione in cases of hepatic cirrhosis. Gut 1965; 6(5):472–6).
2.5.5 Silymarin
Silymarin is the extract from the seeds of the milk thistle plant Silybum marianum which is found in dry rocky soils of Southern and Western Europe and in some parts of the U.S. Silymarin extract is composed of three flavonoid molecules (silybin, silydianin, and silychristin). Silymarin is thought to have positive effects in the treatment of various forms of liver diseases and has been used for over 2,000 years. It is currently the most well researched plant extract in the treatment of liver disease (with over 450 published peer review papers).
Silymarin and one of its structural components, silibinin, have been well characterized as hepato-protective substances (Valenzuela A. et al. Biochemical bases of the pharmacological action of the flavonoid silymarin and of its structural isomer silibinin. Biol Res. 1994; 27(2):105–12). When ingested, silymarin undergoes enterohepatic recirculation and has higher concentrations in liver cells. Numerous studies have reported-the hepatoprotective effects that silymarin has against a wide variety of toxins, including acetaminophen, ethanol, carbon tetra-chloride, and D-galactosamine, and against ischemic injury, radiation, iron toxicity, and viral hepatitis (McPartland J. M. Viral hepatitis treated with Phyllanthus amarus and milk thistle (Silybum marianum). Complementary Medicine International 1996; March/April: 40–42; Berkson B. M. A conservative triple antioxidant approach to the treatment of hepatitis C. Combination of alpha lipoic acid (thioctic acid), silymarin, and selenium: three case histories. Med Klin. 1999; 94 Suppl 3:84–9; Patrick L. Hepatitis C: epidemiology and review of complementary/alternative medicine treatments. Altern Med Rev. 1999; 4(4):220–38; Luper S. A review of plants used in the treatment of liver disease: Part 1. Altern Med Rev. 1998; 3:410–421; Gagliardi B. et al., Results of a double blind study on the effect of silymarin in the treatment of acute viral hepatitis, carried out at two medical centers. Med Klin. 1978; 73:1060–1065; Moscarelli S. et al., Therapeutic and anti-lipoperoxidant effects of silybin-phosphatidylcholine complex in chronic liver disease: preliminary results. Curr Ther Res. 1993; 53:98–102; Morazzoni P. et al., Comparative pharmacokinetics of silipide and silymarin in rats. Eur J Drug Metab Pharmacokinet. 1993; 18:289–297; Hruby K. et al. Chemotherapy of Amanita phalloides poisoning with intravenous silibinin. Hum Toxicol. 1983; 2:183–195; Sabeel A. I. et al. Intensive hemodialysis and hemoperfusion treatment of Amanita mushroom poisoning. Mycopathologia 1995; 131:107–114; Salmi H. A. et al. Effect of silymarin on chemical, functional, and morphological alterations of the liver; A double blind controlled study. Scand J Gastroenterol. 1982; 17:517–521; Buzzelli G. et al. A pilot study on the liver protective effect of silybin-phosphatidylcholine complex (1 dB 1016) in chronic active hepatitis. Int J Clin Pharmacol Ther Toxicol. 1993; 31:456–460; Feher I. et al. Liver-protective action of silymarin therapy in chronic alcoholic liver diseases. Orv Hetil. 1989; 130:2723–2727; Ferenci P. et al., Randomized controlled trial of silymarin treatment in patients with cirrhosis of the liver. J Hepatol. 1989; 9:105–113; Dehmlow C. et al. Inhibition of Kupffer cell functions as an explanation for the hepatoprotective properties of silibinin. Hepatology 1996; 23:749–754). Silymarin has also been shown to slow or reverse liver fibrosis in animals (Boigk G. et al. Silymarin retards collagen accumulation in early and advanced biliary fibrosis secondary to complete bile duct obliteration in rats. Hepatology 1997; 26:643–649).
2.5.6 Lipoic Acid
Lipoic acid, also known as and called interchangeably in this application alpha-lipoic acid, is a naturally occurring coenzyme found in most prokaryotic and eukaryotic microorganisms (Busby R. W. et al. Lipoic acid biosynthesis: LipA is an iron-sulfur protein. J Am Chem Soc. 1999; 121:4706–4707), as well as in many plant and animal tissues (Herbert A. A. et al. Lipoic acid content of Escherichia coli and other microorganisms. Arch Microbiol. 1975; 106:259–266).
Lipoic acid has therapeutic potential in conditions where oxidative stress is associated with liver damage (Bustamante J. et al., Alpha-lipoic acid in liver metabolism and disease. Free Radic Biol Med. 1998; 24(6):1023–39). Specifically, lipoic acid has been found to be useful in reducing serum aspartate transaminase and serum glutamyl transpeptidase, as well as improving liver histology (Marshall A. W. et al. Treatment of alcohol-related liver disease with thioctic acid: a six month randomized double-blind trial. Gut 1982; 23(12): 1088–93).
2.5.7 Vitamin E
Vitamin E is a fat-soluble vitamin that includes eight naturally occurring compounds in two classes designated as tocopherols and tocotrienols (Traber M. G. et al. Vitamin E: Beyond antioxidant function. Am J Clin Nutr. 1995; 62:1501S-9S). Alpha-tocopherol is the most active form of vitamin E in humans, and is a powerful biological antioxidant (Traber M. G. Vitamin E. In: Shils M E, Olson J A, Shike M, Ross AC, ed. Modern Nutrition in Health and Disease. 10th ed. Baltimore: Williams & Wilkins, 1999:347–362; Farrell P. et al. Vitamin E. In: Shils M, Olson J A, and Shike M, ed. Modem Nutrition in Health and Disease. 8th ed. Philadelphia, Pa.: Lea and Febiger, 1994:326–341).
Vitamin E has been shown to protect against liver damage induced by oxidative stress in animal experiments by normalizing liver enzymes (Sun F. et al. Evaluation of oxidative stress based on lipid hydroperoxide, vitamin C and vitamin E during apoptosis and necrosis caused by thioacetamide in rat liver. Biochim Biophys Acta. 2000;1500(2):181–5; Nagita A. et al. Assessment of hepatic vitamin E status in adult patients with liver disease. Hepatology 1997; 26(2):392–7; von Herbay A. et al. Vitamin E improves the aminotransferase status of patients suffering from viral hepatitis C: a randomized, double-blind, placebo-controlled study. Free Radic Res. 1997; 27(6):599–605). There is evidence that vitamin E can act as a supportive therapy to combat liver damage caused by oxidative stress in patients with continuously high levels of ALT even after anti-viral and anti-inflammatory drug therapy (Mahmood S. et al. Effect of vitamin E on serum aminotransferase and thioredoxin levels in patients with viral hepatitis C. Free Radic Res. 2003; 37(7):781–5).
2.5.8 Vitamin B-Complex
Vitamin B-complex generally refers to a selection of nutrients (e.g., thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7 or H), folic acid (B9), and cyanocobalamin (B12)) which have very similar properties and mostly work in synergy.
The therapeutic effects of B vitamins in treating chronic hepatitis have been investigated (Eberhardt G. et al. Controlled study of the therapeutic effect of B vitamins and an anabolic steroid in chronic hepatitis. Dtsch Med Wochenschr. 1975; 100(41):2074–82 (in German; Thaler H. Vitamin therapy in liver diseases. Dtsch Med Wochenschr. 1970; 95(30):1581–2 (in German)). In particular, numerous studies have shown that vitamin B12 is useful in treating hepatitis (Komar VI. Use of vitamin B12 in the combined therapy of viral hepatitis. Vopr Pitan. 1982; (1):26–9 (in Russian)). Cobalamins are stored in high concentrations in the human liver and thus are available to participate in the regulation of hepatotropic virus functions. Cyanocobalamin (vitamin B12), by inhibiting the HCV internal ribosome entry site (IRES)-dependent translation of a reporter gene in vitro in a dose-dependent manner without significantly affecting the cap-dependent mechanism, has a normalizing effect on the level of alanine aminotransferase of the blood (Takyar S. S. et al. Vitamin B12 stalls the 80 S ribosomal complex on the hepatitis C internal ribosome entry site. J Mol Biol. 2002 24; 319(1):1–8).
Citation of documents herein is not intended as an admission that any of the documents cited herein is pertinent prior art, or an admission that the cited documents are considered material to the patentability of the claims of the present application.